uwave is world of mystery (not really..nearly everything can be simulated in puter nowadays). At some frequency bands, most of the RF current is transported, not in the middle of the conductor, but along the very edge. Now, we have experienced that the solder and the gold have sometimes poor coverage and thickness along the line's edges, compared with the flat top side. Therefore, in many cases, the signal has to travel in nickel. In order to get rid of the various problems, we sometimes just skip all platings and use pure copper! All depending on application. If the board is exposed to harsh environment, it woun't work of course. FYI , The resistivity league: Ag 1.6 uOhm.cm, Cu 1.7, Au 2..4, Solder 17 and Electroless Nickel 55-90 uOhm.cm. So, now you can see why nickel may be troublesome at certain frequencies. If you want to learn more, Don Cullen at MacDermid and Bruce Kline at Taconic, have written an interesting paper about various finish vs frequency. 15961/358 Ingemar Hernefjord Ericsson Microwave Systems -----Original Message----- From: TechNet [mailto:[log in to unmask]] Sent: den 27 december 2004 16:53 To: [log in to unmask] Subject: Re: [TN] Immersion gold specification Hi Frank, Why is the Nickel thickness reduced for RF designs? Immersion Gold is typically done after soldermask, so the traces are still copper, and the gold pads become covered with solder after assembly. Therefore, the skin affect wouldn't apply to the nickel. Ryan Grant -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Frank Kimmey Sent: Thursday, December 23, 2004 11:31 AM To: [log in to unmask] Subject: Re: [TN] Immersion gold specification Well, now that Jeff has told you about the standard here is a little more. As Paul says, "it depends" Though ENIG is a great finish for today's designs there are some definite issues with the latest IPC standard. Depending on the type of design you may want to modify the callout to fit your requirements. 1. Use standard as a reference for digital designs (remind your fabricator that "black pad" is not acceptable) 2. Reduce the nickel thickness for RF designs as more nickel creates a bigger barrier for the RF to flow. Personally I callout 3 to 8 microinches of Immersion Gold over 50 to 150 microinches of Electroless Nickel. But then I am doing high powered, low loss required RF. Good Luck and have a Happy Holidays Hope it helps, FNK Frank N Kimmey CID+ Principal PCB Designer Powerwave Technologies Inc Office 916-941-3159 Fax 916-941-3195 Cellular 916-804-2491 -----Original Message----- From: Jeffrey Bush [mailto:[log in to unmask]] Sent: Thursday, December 23, 2004 10:10 AM To: [log in to unmask] Subject: Re: [TN] Immersion gold specification The current ENIG standard is IPC-4552. The spec on thickness for all classes is 2 uinch minimum for gold and 118-236 for nickel. Jeffrey Bush Director, Quality Assurance and Technical Support VERMONT CIRCUITS INCORPORATED 76 Technology Drive - POB 1890 Brattleboro, Vermont 05302 Voice: 802.257.4571.21 Fax: 802.257.0011 http://www.vtcircuits.com -----Original Message----- From: David Harman [mailto:[log in to unmask]] Sent: Thursday, December 23, 2004 1:01 PM To: [log in to unmask] Subject: [TN] Immersion gold specification Hope the network out here has a great holiday and successful new year. I have one last question for this year regarding plating standards and specifications. I am trying to call out gold immersion specification over nickel on my PCBA. My understanding is Mil-G-45204 type ll is no longer a valid specification. Is the industry standard 3 micro inches max - 1 micro inch min. (As long as the process can be controlled you should not have any nickel migration.) Is this correct. Can some one tell me how I would spec this out on my drawing and what standard is used in the industry for gold immersion over a an absolute minimum of .00005 nickel. Thanks David Harman --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------